1. Field of Invention
The present invention relates to a method and a device for dispersing and dampening impact forces.
2. Description of Related Art
There are a many applications where it is highly desirable, if not absolutely vital, to effectively disperse and dampen impact forces directed toward a person or an object. One such application is in the field of body armor.
Body armor, which may include a ballistic vest (also known as a “bullet-proof” vest) alone or in combination with other protective clothing such as, for example, a helmet, ballistic shoulder armor and/or ballistic leg armor, is worn to protect a wearer's body from being pierced by gun-fired projectiles and explosive fragments. The most commonly used body armor is a ballistic vest, which protects the wearer's torso and thus the wearer's vital organs from penetration injuries.
In the past, ballistic vests were formed using steel plates and/or other rigid, heavy materials. Studies showed that heavy, uncomfortable body armor was less likely to be worn than lighter, more comfortable body armor. Thus, ballistic vest manufacturers developed lighter weight materials. Most modern ballistic vests are made from synthetic fabrics comprising ballistic fibers (e.g., KEVLAR®), which may be supplemented with ceramic plates and/or metal plates. This type of body armor is generally referred to as “soft body armor”.
The impact of a projectile against a ballistic vest directs an impact force toward the torso of the wearer. Unless the impact force is adequately dispersed, the impact force can produce blunt force trauma injuries to the wearer of the ballistic vest, which can result in severe internal injuries or death. Thus, ballistic vest manufacturers must also devise ways in which to disperse the impact forces transferred through the ballistic vest toward the wearer's torso.
One way in which to gauge the impact force transferred through a ballistic vest to the torso of a person wearing the ballistic vest is to measure the amount of deformation the ballistic vest permits in a backing material when the ballistic vest is struck with a projectile under controlled conditions. Throughout the instant specification and in the appended claims, the term “deformation” means the maximum depth measurement of backface signature in the backing material caused by a fair hit that does not penetrate the ballistic vest when tested in accordance with the testing standards set forth in National Institute of Justice (NIJ) Standard 0101.04 Rev. A (June 2001), entitled: “The Ballistic Resistance of Personal Body Armor”, which is hereby incorporated by reference in its entirety Section 4.6 of that standard provides in pertinent part that any designated depth measurement of backface signature in the backing material greater than 44 mm by any fair hit shall constitute a failure.
In order to meet the minimum requirements of NIJ Standards (Note: NIJ Standard 0101.04 has been superseded by more recent standards, but is nevertheless referenced for this specification), some ballistic vest manufacturers enclose one or more soft foam-like pads within the ballistic vest such that they are positioned proximal to the wearer's body when the ballistic vest is properly donned. The foam-like pads are intended to disperse the impact force over a larger area of the wearer's torso and thereby dampen the deformation and blunt force trauma directed to the wearer's torso. Other ballistic vest manufacturers employ inserts containing viscoelastic polymers, ceramic plates and/or various metallic mechanical structures for this purpose.
One of the drawbacks with the use of such prior art impact force dispersion and dampening devices is that they tend to be relatively bulky and heavy. This can be particularly problematic when the wearer of the ballistic vest is deployed in a high temperature environment such as a desert or inside an enclosed motor vehicle. Because the ballistic vest is often worn during an entire shift or period of deployment in close contact with the wearer's body, the vest can retain significant body heat, causing the wearer to perspire. Perspiration can weaken the strength and integrity of the ballistic fibers used to form the armor, and thereby diminish the penetration efficiency of the ballistic vest. Furthermore, the accumulation of perspiration in the vest creates additional weight and makes the vest uncomfortable. This can motivate a wearer to at least partially remove the ballistic vest, thereby exposing the wearer to harm.
In addition to ballistic vests, there are many other applications in which it would be highly desirable to be able to effectively disperse and dampen impact forces directed at a person or an object using a lightweight device that does not promote heat retention and perspiration. Such other applications include sporting goods (e.g., baseball catcher's equipment, football pads etc.), medical devices, automotive and aircraft interiors and the like.